This invention relates to a keyboard musical instrument and, more particularly, to a silent system to be installed in a composite keyboard musical instrument and a composite keyboard musical instrument for selectively performing a piece of music in acoustic tones and in electronic tones.
The composite keyboard musical instrument is equipped with a hammer stopper. The user instructs the composite keyboard musical instrument to change the hammer stopper between a free position and a blocking position before his or her performance. A user is assumed to perform a piece of music in acoustic tones. The user instructs the composite keyboard musical instrument to change the hammer stopper to the free position. The composite keyboard musical instrument maintains the hammer stopper out of the trajectories of the hammers so that the hammer stopper does not impede the hammer motion. While the user is fingering a passage on the keyboard, the depressed keys give rise to the free rotation of the hammers, and the hammers strike the strings. The strings vibrate for generating the acoustic tones. On the other hand, when the user wants to practice the fingering without the acoustic tones, he or she instructs the composite keyboard musical instrument to change the hammer stopper to the blocking position. Then, the hammer stopper is moved into the trajectories of the hammers. In this situation, even though the user practices the fingering on the keyboard, the hammers rebound on the hammer stopper before striking the strings, and any acoustic tone is never generated. A set of key sensors monitors the keys, and periodically reports the current key positions to a controller. The controller analyzes the pieces of positional data information to see whether or not the user depresses and releases any one of the keys. If the controller notices the user depressing a key, the controller produces music data codes representative of an electronic tone to be generated, and the electronic tone is, by way of example, generated by a headphone. On the other hand, when the controller notices the user releasing the key, the controller produces a music data code representative of the decay of the electronic tone, and the electronic tone is decayed. Thus, the composite keyboard musical instrument permits the user to practice the fingering without disturbance to the neighborhood. The state to permit the user to perform in acoustic tones is hereinbelow referred to as xe2x80x9cacoustic sound modexe2x80x9d, and the state to permit the user to practice fingering without the acoustic tones is referred to as xe2x80x9csilent modexe2x80x9d.
When a user depresses a key, the associated action unit gives rise to rotation of the hammer around the associated flange. The jack escapes from the associated hammer when it is brought into contact with the regulating button. The hammer starts the free rotation through the escape. The escape from the hammer causes pianists to feel the key touch unique. For this reason, the hammers are to rebound on the hammer stopper after the escape and before striking the strings. The distance between the hammer shank at the escape and that at the strike is so short that the manufacturer encounters a difficulty in appropriately locating the hammer stopper. It is said that the distance is of the order of 2 millimeters. If the hammer stopper is too close to the rest positions, the hammers are brought into contact with the hammer stopper before the escape, and the hammers are pinched between the jack and the hammer stopper. On the other hand, if the hammer stopper is widely spaced from the rest positions, the tips of the hammers reach the strings, and the hammer stopper imperfectly prevents the strings from the hammers.
In order to perfectly prevent the strings from the hammers without changing the key touch, the manufacturer changes the timing to escape in the silent mode earlier than that in the acoustic sound mode. However, the solution is the second best, because the pianist feels the key touch changed a little. Even so, the solution is realistic, and a prior art composite keyboard musical instrument is equipped with a means for changing the escape timing.
The prior art means for changing the escape timing is implemented by a spacer and an actuator connected thereto. The spacer is flexible, and is swingably supported by the shank flange rail. The solenoid-operated actuator urges the spacer to enter the space between the toes and the regulating buttons, and evacuates the spacer from the space. Thus, the spacer is moved into and out of the trajectories of the toes of the jacks.
While the user is playing a piece of music in the acoustic sound mode, the solenoid-operated actuator keeps the spacer out of the trajectories of the toes, and the toes are directly brought into contact with the regulating buttons so as to give rise to the escape at the usual timing.
When the user establishes the composite keyboard musical instrument in the silent mode, the solenoid-operated actuator urges the spacer to enter the trajectories of the toes. In this situation, the user is assumed to depress a key. The front position of the key is sunk, and, accordingly, the rear portion of the key is raised. The rear portion pushes the whippen assembly so as to give rise to the rotation around the associated flange. The toe is getting closer to the regulating button, and is firstly brought into contact with the spacer. The spacer is resiliently warped, and is brought into contact with the regulating button. Then, the jack is rotated around the whippen assembly, and escapes from the hammer. Thus, the spacer hastens the escape of the jack.
The users appreciate the prior art composite keyboard musical instrument equipped with the means for changing the escape timing, and practice the fingering on the keyboard in the silent mode in the key touch close to that in the acoustic sound mode. The means for changing the escape timing is simply referred to as xe2x80x9ctiming changerxe2x80x9d hereinbelow.
The composite keyboard musical instrument is manufactured and sold in the market. Persons who begin pianos may select the composite keyboard musical instrument instead of the acoustic piano. However, the users who have already owned acoustic pianos may attach themselves to the familiar acoustic pianos. Other users may think the composite keyboard musical instrument expensive. For this reason, the manufacturer receives the order for retrofitting the acoustic piano to the composite keyboard musical instrument.
The manufacturer usually sends workers to user""s home, and retrofits the acoustic piano to the composite keyboard musical instrument thereat. The hammer stopper, the timing changer and the electronic tone generating system are to be installed in the acoustic piano at user""s home. This means that only portable tools and jigs are available for the retrofitting works. The prior art hammer stopper is as long as the array of hammers so that the workers have a difficulty in assembling the long hammer stopper with the acoustic piano. For this reason, the retrofitting works are not easy. In other words, the workers wish the hammer stopper, the timing changer and the electronic tone generating system to be easy to build.
Another difficult work is to form a hole in a projection. FIG. 1 shows a standard grand piano 1. The standard grand piano has a keyboard 2, and a metal beam 3 extends in the lateral direction. Though not shown in FIG. 1, an array of action units and hammers are installed in the space between the keyboard 2 and the metal beam 3a, and strings are stretched over the hammers. Although an iron plate reinforces a wood frame, the strings exert a large amount of tension on the iron plate. A projection 3 is formed on the iron plate in order to restrict deformation. The projection 3 occupies a part of the space over the hammers. In the work of retrofitting the grand piano 1 to the composite keyboard musical instrument, the workers install a hammer stopper 4 into the space. However, the projection 3 crosses the space to be occupied by the hammer stopper 4. The workers machine the projection 3 for forming a hole therein, and pass the hammer stopper 4 through the hole. Since the workers are to form the hole with a portable machine, a large amount of time and labor is required for the machining.
Still another difficulty encountered in the retrofitting work is the dispersion in height of the strings. The strings are measured from the upper surface of the key bed to the lowest points of the strings, and the distance therebetween is defined as xe2x80x9cheightxe2x80x9d. The manufacturer adjusted the height to a target value, and delivered the grand piano. However, a large amount of tension has been continuously exerted on the iron frame, and the iron frame tends to be deformed. The deformation is usually observed in old pianos. The deformation is causative of the dispersion in the height of the strings. When the manufacturer receives the order for retrofitting the old piano to the composite keyboard musical instrument, the workers install the hammer stopper inside the piano case, and try to locate the hammer stopper at the appropriate position where the hammers rebound after the escape and before reaching the strings. However, if the dispersion in height has been taken place, the workers hardly pass the hammer stopper through the positions appropriate to the individual hammers.
It is therefore an important object of the present invention to provide a silent system, which is simple and makes a work for retrofitting an acoustic keyboard musical instrument to a composite keyboard musical instrument easy.
It is also an important object of the present invention to provide a composite keyboard musical instrument, which is equipped with the silent system.
The present inventors contemplated the problems inherent in the prior art silent system and the prior art composite keyboard musical instrument. First, the inventors split the hammer stopper into two parts, and installed the two parts on both sides of the projection 3 together with the timing changer and the electronic tone generating system. However, the split hammer stopper and the timing changer required individual link mechanisms. The individual link mechanisms consisted of bulky links, individual actuators. Even though an actuator was shared between the split hammer stopper and the timing changer, the actuator was to be connected to the two parts of the split hammer stopper and the timing changer through three series of links. The link mechanism for the split hammer stopper and the link mechanism for the timing changer caused the internal arrangement tight and complicated, and the retrofitting work consumed a large amount of time and labor.
The present inventors thought it preferable to reduce the bulky links, and developed a new mechanism for the split hammer stopper and the timing changer.
In accordance with one aspect of the present invention, there is provided a composite keyboard musical instrument selectively entering an acoustic sound mode and another mode for reducing the loudness of acoustic tones comprising plural keys respectively assigned pitches different from one another and independently moved between respective rest positions and respective end positions, plural vibratory members respectively associated with the plural keys for generating the acoustic tones having the pitches identical with the pitches assigned to the associated keys in the acoustic sound mode, plural vibration generators associated with the plural vibratory members, respectively, and selectively moved along respective trajectories for generating vibrations in the associated vibratory members, plural action units respectively connected between the plural keys and the plural vibration generators and causing the associated vibration generators to initiate the motion along the trajectories at a timing on the way toward the end positions after the associated keys start the motion toward the end positions, and a silent system including a stopper provided between the plural vibratory members and the plural vibration generators for causing the vibration generators to rebound thereon in the aforesaid another mode and split into plural parts independently movable between respective free positions in the acoustic sound mode and respective blocking positions in the aforesaid another mode, an actuator for generating a power, a timing changer for changing the timing at which the vibration generators initiate the motion and plural transmission mechanisms selectively connected in parallel between the plural parts and the timing changer and transmitting the power to the plural parts for concurrently changing the plural parts between the respective free positions and the respective blocking positions and to the timing changer for causing the timing changer to change the timing.